#!/usr/bin/env python
#Author: Shriphani Palakodety

import math

def solve(x):
	return 2*((5+(x)**3)**(1.0/4.0))

nums=[0, 1.0/4.0, 2.0/4.0,3.0/4.0,1.0, 5.0/4.0, 6.0/4.0, 7.0/4.0, 2.0 ]
solu = []
for i in xrange(1,len(nums)):
	solu.append(solve((nums[i]+nums[i-1])/2))
print sum(solu) * 1.0/4.0